Water cooled cast iron or cast aluminum engines are used throughout the automotive industry to power modern cars and trucks. During fabrication, the engine blocks of such engines are formed by pouring molten metal into a mold formed in casting sand. When the molten metal cools and solidifies to form the metal block, the casting sand is removed from around and through the block, which is further machined to form the finished part. The process of removing the casting sand, particularly from inside the engine coolant passageways of a cast engine block, is not trivial. Typically, the blocks are tumbled to dislodge the casting sand and their coolant passageways are thoroughly flushed with a cleaning solution.
While the cleaning and flushing process cleans most of the casting sand from the coolant passageways of an engine block, there nevertheless remains a small amount of sand that is not removed because it is trapped in crevices or partially imbedded in the walls of the passageways. This sand becomes a problem during normal operation of a vehicle in which the engine block is installed because the grains of casting sand are slowly dislodged by the circulating engine coolant and entrained in the flow of coolant through the water pump and coolant passageways of the engine. The abrasive effect of this sand tends to erode rotors and seals within the water pump and can collect at certain locations within the coolant passageways creating partial blockages and "hot spots" that can eventually destroy an engine. In addition to casting sand, other contaminates such as rust flakes and calcified minerals can become entrained in the coolant flow over time.
Another common problem related to vehicle coolant systems is the rupturing or blowout of a vehicle's heater core as a result of unusually high coolant pressures. Such pressures typically occur during extreme acceleration or other high engine revolution when the water pump is operating at high speeds. While the problem is more common in high performance high revolution engines, it nevertheless can also occur in common passenger vehicles. A heater core blowout is particularly expensive to repair because the heating system of the vehicle must be disassembled, which usually entails disassembly of the dash and other major components of the vehicle. In addition, a go heater core blowout can quickly drain a vehicle of its coolant, resulting in overheating and ruination of the vehicle's engine.
Some attempts to filter or remove casting sand and other sludge entrained within a vehicle's coolant flow have been made. For example, U.S. Pat. No. 3,773,107 of Bener discloses a sump trap located at the inlet of a vehicle's radiator to collect entrained sludge. U.S. Pat. No. 5,662,791 of Hurst et al. discloses an in-line filter connected in the return hose of the cooling system to filter entrained sludge particles from the flow. Other general purpose filters and valves are illustrated in U.S. Pat. No. 4,166,792 of Offer et al., U.S. Pat. No. 4,183,812 of Rosaen et al., U.S. Pat. No. 4,697,617 of Bourke et al., U.S. Pat. No. 4,743,365 of Noland, and U.S. Pat. No. 5,181,534 of Hashida et al. While the devices disclosed in these patents can be effective in removing or filtering entrained sludge particles from engine coolant, none of them addresses the problems caused by heater core overpressure. Furthermore, applicant is aware of no device that simultaneously removes entrained sediments from the coolant and provides pressure regulation for a heater coil under conditions of extreme coolant pressure to prevent heater core blowout.
Accordingly, there exists a need for an effective and efficient method and apparatus for removing entrained casting sand and sludge from the coolant flow within a vehicle engine while at the same time automatically regulating coolant pressure to the coils of a vehicle's heater core. It is to the provision of such a method and apparatus that the present invention is primarily directed.